American Board of Internal Medicine (ABIM) Certification Practice Exam

Which of the following is NOT a diagnostic criterion for allergic bronchopulmonary aspergillosis?

1. Peripheral eosinophilia greater than 1000/µL

2. Serum IgE levels over 1000 U/mL

3. Reactivity to Aspergillus on skin testing

4. Positive sputum culture for Streptococcus

The correct answer is: Positive sputum culture for Streptococcus

In the context of allergic bronchopulmonary aspergillosis (ABPA), the diagnostic criteria focus on identifying responses to Aspergillus species and relevant immunological markers. The presence of peripheral eosinophilia greater than 1000/µL, elevated serum IgE levels over 1000 U/mL, and reactivity to Aspergillus on skin testing are all recognized components that indicate an allergic response to Aspergillus, which is central to diagnosing ABPA. Peripheral eosinophilia is significant because it reflects an allergic response that commonly occurs in ABPA patients. Similarly, high levels of serum IgE suggest a hyperreactive immune system, often seen in allergic conditions, including ABPA. Skin reactivity to Aspergillus demonstrates a specific immunologic reaction to the fungus, further solidifying the diagnosis. In contrast, a positive sputum culture for Streptococcus does not relate to the diagnosis of ABPA. Streptococcus is not involved in the pathophysiology of ABPA and thus does not provide relevant information regarding an allergic response to Aspergillus species. This makes it the criterion that is not diagnostic for ABPA.